1. Field of the Invention
The present invention relates to a piezoelectric actuator, in which a piezoelectric layer is interposed between individual electrodes and common electrodes, and a liquid discharge apparatus provided with the same.
2. Description of the Related Art
A piezoelectric actuator has been hitherto known, including a channel unit, a top plate (vibration plate) which is arranged on an upper end of the channel unit, and a piezoelectric layer which is stacked on the vibration plate, wherein individual electrodes facing pressure chambers are arranged on one surface of the piezoelectric layer, and a first constant electric potential electrode which faces substantially central portions of the individual electrodes and a second constant electric potential electrode which faces both end portions in the transverse direction of the individual electrodes are arranged on the other surface of the piezoelectric layer. In the piezoelectric actuator constructed as described above, the portion, of the piezoelectric layer, facing the individual electrode and the first constant electric potential electrode and another portion, of the piezoelectric layer, facing the individual electrode and the second constant electric potential electrode are simultaneously deformed. Accordingly, the portions, of the piezoelectric layer and the vibration plate, which face the pressure chambers are deformed. Accordingly, it is possible to avoid the so-called crosstalk which would be otherwise caused such that the deformation of any portion of the piezoelectric layer facing a certain pressure chamber is transmitted to another portion facing another pressure chamber.
Another piezoelectric actuator has been known, including a vibration plate, a piezoelectric layer which is stacked on an upper surface of the vibration plate, pressure chambers which are aligned in two arrays in one direction on a surface, of the piezoelectric layer, facing the vibration plate, individual electrodes which are arranged at portions of the vibration plate facing the pressure chambers, a common electrode which is arranged to extend continuously while ranging over the plurality of pressure chambers on the other surface, of the piezoelectric layer, not facing the vibration plate, a driver IC which is arranged on the upper surface of the vibration plate, and wiring lines which are led out to the upper surface of the vibration plate and which connect the driver IC and the electrodes to one another. In the piezoelectric actuator constructed as described above, the wiring lines, which are connected to the individual electrodes, are laid out on the same surface, of the vibration plate, as the surface on which the individual electrodes are arranged, and the wiring lines are connected to the driver IC. Therefore, the reliability is enhanced for the connection between the individual electrodes and the driver IC. In other words, the various electrodes such as the individual electrodes and the like are connected to the driver IC without using any wiring member such as FPC or the like. Therefore, the reliability is enhanced for the electrical connection and the physical connection between the electrodes and the driver IC.